Mechanical characteristics of tumor and healthy tissue in the brain differ but slightly. The task of designing a system that is able to differentiate tissue dignity with high sensitivity is of great importance in neurosurgery. Even when localization of tumor by use of preoperative imaging techniques provides the surgeon with valuable information to decide where and what to resect, the brain shift due to change in pressure during skull opening demands the surgeon to define the limits of the tumor using tactile and visual differentiation. This paper contains a general description of the tactile sensor system based on a piezoelectric bimorph. The main parts of the measurement system are described and the selection of the electrical parameters for tactile differentiation is justified. Results are discussed for a series of measurements at different concentrations in gelatin phantoms.